A Novel Deployable Telescope for Earth Observation

The Surrey Space Centre (SSC) and Surrey Satellite Technology Ltd (SSTL) have collaborated in a Centre for Earth Observation Instrumentation (CEOI) sponsored project to design a deployable Cassegrain telescope. Optical telescopes are currently flown with a fixed focal length, set by the desired magnification, which limits their use to larger satellites. Incorporating a deployable system, to extend to the fixed length from a smaller volume, could open the door for smaller satellites to carry larger optical telescopes, making Earth observation more accessible for research and businesses. The aim of this project was to increase the capability of small satellites for Earth observation by demonstrating a proof of concept breadboard and development model of a deployable Cassegrain telescope. The design shows excellent repeatability when deployed and meets the stiffness requirements to avoid on board micro-vibrations distorting images. The design uses three concentric composite barrels that deploy using a leadscrew-gear train. The design, analysis and test campaign is documented in this paper, as well as the lessons learnt on completion of the project.